In the processing of glass bottles and the like for shrink application thereon of foam polyolefin sleeves, such as polyethylene, it is desirable to shrink the sleeves onto the entire outer peripheral surface of the bottle to substantially encapsulate the surface area in the plastic sleeve, thus providing further cushioning of the glass surface and glass fragment retention capability should the bottom be broken. Bottles, and especially larger volume carbonated beverage bottles, include a relatively large diameter body that is for the most part cylindrical, a tapered or rounded shoulder portion that merges into a relatively small diameter neck, and a top "finish" or mouth portion over which there is applied a sealing closure after the bottle is filled. By way of illustration, a typical bottle of this configuration may have a major body diameter of 4-5 inches and a neck diameter of 1-2 inches.
In the use of certain pre-oriented and heat shrinkable foamed polyolefin materials, of which foamed polyethylene is a good example, the material upon first stages of heating achieves a very limp and pliable condition. It has been found in the production of the full sleeve coverage on a bottle, as mentioned, that the usual practices of heat immersion of the bottle and said polyolefin sleeves result in the upper section of the sleeve opposite the neck region of the bottle upon achieving the very limp condition in the initial heating thereof will slump or fold over itself. After initial heating (the very limp stage), and a sufficient additional time of heating, the material shrinks snugly onto the bottle and the segment that is folded over, it having also shrunken, produces a defective coating, i.e. offware, making the package unsalable.
In U.S. Pat. No. 3,843,316, there is disclosed a machine for the production of heat shrinkable plastic sleeves on articles, such as bottles, in which the bottles are conveyed by rotatable chucks supporting the articles on spaced centers along a conveyor. The apparatus of this patent applies the sleeve over the major or larger body diameter segment of the bottle and into the sloping shoulder, and the sleeve is a pre-oriented foam polystyrene. After the heat shrinkable polystyrene sleeves are placed on the articles, the conveyor travels through a heat applying device or oven, wherein the temperature is maintained sufficiently to rapidly shrink the sleeves onto the article surface in a snug, surface conforming relationship. A rotary element of the chucks engages a stationary rail imparting rotation to the chucks and articles held thereby during their travel along the span of the oven during heat immersion of the articles and sleeves. The articles are rotated in the oven in response to travel therein for peripheral distribution of heat during shrinking of the sleeve.